The broad objectives of the proposed research are to determine the mechanism by which vitamin E functions in the differentiation, proliferation and maintenance of the integrity of the testicular germinal epithelium. Studies by the present investigator indicate that the regulation of polyenoic fatty acid metabolism is important in the development and maintenance of the germinal epithelium and that vitamin E has a role in this regulation. Preliminary work on the synthesis of linoleate-derived fatty acids and their incorporation into testicular membranes as well as into prostaglandins show there are differences between immature and adult rats and between animals fed control and vitamin E-deficient diets. The immediate objective of this study is to study the synthesis and turnover of polyenoic fatty acids in the testes of intact rats during development of the germinal epithelium, as well as in vitro in isolated subcellular preparations of testis. The synthesis of prostaglandins by testis and the possible role of these compounds in regulating testicular function is also under investigation.